North Korea on Tuesday declared it had successfully tested an intercontinental ballistic missile (ICBM), prompting the usual response of condemnation and consternation from the international community. The announcement on North Korean state television said that the launch of a Hwasong-14 missile had been ordered and supervised by the reclusive regime's leader, Kim Jong Un.

The United States confirmed the ICBM test launch, which marks a major step forward in North Korea's effort of  developing a nuclear-armed missile that could reach the United States. Pyongyang has conducted missile-related activities at an unprecedented pace since the start of last year, raising tensions.

Meanwhile, US President Donald Trump is piling pressure on China to use its diplomatic and economic clout over North Korea to persuade Pyongyang to stop its nuclear and missile activities.

Just a few days ago, a group of six high-ranking American diplomats and politicians endorsed a letter that was sent to Trump, addressing the North Korea problem and trying to persuade the US president that there are no alternatives to a diplomatic path in order to find a solution to the gridlocked situation.

The letter was endorsed by former US Secretary of Defense William J. Perry, former US Secretary of State George P. Shultz, former US  Senator Richard G. Lugar, former Governor of New Mexico Bill Richardson, nuclear scientist Siegfried Hecker of Stanford University and Robert L. Gallucci, Distinguished Professor in the Practice of Diplomacy at Georgetown University.

In a DW interview, Gallucci talks about the message he and the other experts aimed to pass on to the president - and the potential impact of the latest North Korean missile test.

DW: North Korea is steadily proceeding on its path and working on the development of a nuclear-armed missile that could reach US soil. What does this latest provocation mean for the already tense situation between Pyongyang and Washington?

Robert L. Gallucci: I think it clearly means that the leadership in North Korea intends to keep up pressure on the United States and maybe also on other countries in the region like South Korea and Japan. Perhaps it's a tactic they use to secure certain concessions such as reducing the intensity of the joint military exercises that South Korea and the United States have undertaken traditionally.

I don't think it was an accident that the test took place as Americans prepared to mark the US Independence Day on July 4.

And the idea of undertaking their position of not responding to verbal statements and military steps taken by the United States and its allies in the region to indicate to the North Koreans that what they are doing is provocative and unacceptable. Those two words "provocative" and "unacceptable" don't sound like they have much force in the face of what the North Koreans are doing, and I suspect that is why the North Koreans are doing it.

President Trump reacted on Twitter, asking in reference to Kim Jong Un, "Does this guy have anything better to do with his life?" and saying, "Hard to believe that South Korea… and Japan will put up with this much longer." In your opinion, are those 140-character responses an appropriate way to deal with one of the most dangerous flashpoints in the world?

Well, your question suggests that I should evaluate the appropriateness of my president's responses to this. I think a lot of Americans, and myself included, are trying to adjust to the president of the United States and the way he interacts with international leaders as well as the press in the United States and others. It is at least unusual to respond to these issues on Twitter. But the president has said this is his method of communicating, at least sometimes. I don't think I want to go beyond that. However, I do think it is unusual.

The significance of his tweets really relates to the words that he used about our treaty allies, wondering whether they will long continue to accept this kind of activity by the North - this is something that I hope our treaty allies would not decide alone but would decide in consultation with us. And we would together determine what would be a prudent response to North Korea.

Last week, you, together with five renowned experts, including former US secretaries of state and defense as well as a well-known nuclear scientist who actually visited the North's nuclear facility, endorsed a letter sent to Donald Trump, urging him to begin discussions with North Korea. In light of the latest missile test, the letter seems to have come at the right moment. But what prompted you to endorse the letter?

We didn't draft the letter; we were just invited to endorse it. All of us read the letter carefully before signing it. That said, I completely share the sentiment of the letter and am pleased to have been in the company of other gentlemen for whom I have great respect.

The thrust of the letter is that we hope the president of the United States looks at the gravity of the situation and considers ways of engaging with North Korea, which eventually might lead to negotiations and defuse the tensions.

If this is not done in the near term, then we risk the possibility that there will be an incident that could escalate and we could have a conventional armed engagement on the Korean Peninsula. We fear another war on the Korean Peninsula and we hope that it can be avoided.

Have you received any response from the White House so far?

I haven't received any reaction until now. I don't know if anybody else did, and I certainly don't expect a reaction. That's not what I am interested in; what I am interested in is putting before the senior leadership the joint view of people who have had experience over the years and held senior positions in government, and ask that the administration to give that some consideration.

Given the ongoing tensions on the Korean Peninsula, how dangerous has the situation become in your view?

There is a possibility that this situation could get very bad very quickly. The structure of the interaction right now is that North Korea has made it very clear that they wish to develop an ICBM. We have seen tests relevant to such a missile. But President Trump has stressed it wouldn't happen and Defense Secretary James Mattis has said the risk of that is almost already upon us.

So confrontation has already been, in a sense, declared, or at least the structure of such a confrontation: The North Koreans attempt to test an ICBM, and the United States attempts to prevent it. And that is the kind of incident that could, it seems to many of us, escalate into an armed confrontation.

If you believed the North Koreans, that confrontation could have begun to happen yesterday. But I don't believe that it was an ICBM that they tested today from what I have read in the press so far. But we could be on the verge of that kind of confrontation. I think it is a dangerous situation that all those involved should try to defuse as soon as possible before there is loss of life.

At the end of your letter, you speak of a "window of opportunity" - maybe even the last one - to stop North Korea's weapons programs. Do you still see this window after what happened last night?

The test in my view is not definitive. Even if it had been an ICBM test, the situation isn't irretrievable at this point unless one of the parties decides it's irretrievable and takes action and causes loss of life and probably then leads to escalation. The situation is not irretrievable, certainly if the parties decide they wish to get together and to have talks, at least talks about talks about negotiation, if not the initiation of actual negotiations. That would be a step in the right direction. 

You mentioned that a high-ranking presidential envoy should be sent to North Korea - and in return for the talks, Pyongyang should announce a freeze of its nuclear and ballistic tests. How likely do you think this is? (North Korea experts have told me that for Pyongyang, diplomacy and further development of nuclear and ballistic missiles aren't mutually exclusive ... and that North Korea has always made it very clear that its nuclear policy is not negotiable.)

A couple of points here: First, nobody likes to have negotiations when the other side is putting pressure on them. It is bad in terms of domestic support for negotiations; it is bad in terms of the negotiator attempting to have standing in the negotiations.

I have a little experience here, and what we made clear 25 years ago when we negotiated the Agreed Framework with the North Koreans was that while we are negotiating, we don't expect you to make progress on your weapons program. So while we were negotiating, at the time we said you may not separate plutonium, you may not do nuclear weapons tests. We had a series of things. We wanted to freeze the situation.

The intent of our letter was the same. In other words: We don't want North Koreans to enter a negotiation in which while we are talking, they are building. That is not a good idea from our perspective. While we are talking, let us agree that that kind of thing will not happen, and if talks collapse, you can go back to your building. If they succeed, then maybe there will be something of a moratorium or an end to a certain kind of testing.

So it is not a proposition - in the letter - without precedence. This is the kind of thing we've done before.

Second, I think anybody who listens and believes North Koreans' statements - that they are a nuclear weapons state and they always will be, and they'll never give up their nuclear weapons - confuses me. The North Koreans very often have said things and used the word "never" and then they've come around and seen the wisdom of doing a certain thing. So I would say that when we hear the North Korean position, we've got to understand that they are serious about it, but it doesn't mean that the issue is off the table.

I wouldn't engage in talks with the North Koreans unless there is a possibility that at the end of these talks the Korean Peninsula would be free of nuclear weapons. That would be the objective of our negotiations or at least the objective for our side. The North Koreans would have their own. I don't believe there is any reason to take North Koreans' declarations as definitive for all times.

In the past, several top US diplomats engaged in negotiations with North Korea. Who could be the right person to serve as a representative of the Trump administration and negotiate with Pyongyang now? Do you have anyone in mind?

I don't. There ought to be someone with standing within this administration, someone with standing in the international community to talk on behalf of the United States with the North Koreans. I think a senior envoy would be a good idea, but I had no particular candidate in mind.

Robert L. Gallucci is a Distinguished Professor in the Practice of Diplomacy at Georgetown University in the United States. He was chief US negotiator during the North Korean nuclear crisis of 1994.

The interview was conducted by Esther Felden.