By Michael D. Mosettig, former Foreign Editor of PBS News Hour 

Reflecting his country's increasingly pivotal role in the world's major crises, German Foreign Minister Frank-Walter Steinmeier can count on a full house when he makes an address in Washington. And with his increasingly visible role comes increasingly direct talk to his American interlocutors and audiences on issues from Ukraine to Iran.

At the Center for Strategic and International Studies, Steinmeier focused most of his remarks on Ukraine. The story has slipped from the front pages of U.S. media as a fragile ceasefire between the Kiev government and Russian supported separatists, a deal primarily negotiated between Germany, France and Russia, slowly takes hold and spreads in the embattled east. That fragility, however, has only slightly quieted the Washington debate, inside the Obama Administration and in Congress, over providing lethal weapons to Ukrainian government forces.

The arms issue was the major point of contention that Steinmeier addressed, repeating to a Washington audience what he has said frequently in Germany and Europe and what he wrote in New York Times op-Ed: now is not the time to escalate the crisis with weapons. 

Steinmeier acknowledged the accord reached in Minsk last month is fragile and there is still much for Russia and its separatist allies to implement. But sending arms to the government side would only lead the Moscow government of Vladimir Putin to step up its arms shipments. Repeatedly, quoting former U.S. Secretary of State Henry Kissinger and others, Steinmeier said, "we need strategic patience."

"There is no guarantee our approach will lead to success, but there is no guarantee for the alternative," said Steinmeier, who is the leader of the Social Democrats in coalition with Chancellor Angela Merkel's Christian Democrats.

But, in response to questions and switching to German from his English text, the minister said, "we would be in a different ball game," if the separatists captured the city of Mariupol, described as the land bridge that now separates Russia from recently annexed Crimea. There was fighting around the city last month, and Steinmeier acknowledged that its capture would mark the failure of the Minsk agreement.

Ukraine was not the only issue on which the diplomat-politician showed his willingness to wade into American debates, all the while saying he was not doing that. He was asked his opinion of the latest hot button Washington dispute over the letter 47 Republican Senators sent to the Iranian leadership that a nuclear deal with the Obama Administration would not hold either in the Senate or if the GOP wins the 2016 elections.

Steinmeier said the letter undermines a key gain in the talks involving the U.S. Along with Russia, Britain, France, China and Germany aimed at persuading Iran to give up any ambitions for nuclear weapons. Until now, he said, the burden of credibility was on Iran.

After the Senatorial letter, he added, "Iran can now ask us if we are credible."