BRUSSELS - NATO chief Jens Stoltenberg has demanded Russia end its naval standoff with Ukraine, but refused to pledge new support for Kiev as the alliance seeks to avoid escalating the crisis.

Foreign ministers from the 29 allies were expected to meet Ukraine's foreign minister on Tuesday to discuss last week's incident in the Sea of Azov, in which Russian forces seized three Ukrainian ships and 24 sailors.

Ministers will also tackle the Intermediate Range Nuclear Forces (INF) treaty, a major Cold War accord which Washington has announced it will abandon in response to Russian violations, with Stoltenberg promising a "measured, proportionate" response.

Ukraine's President Petro Poroshenko looks likely to be disappointed in his call for NATO to deploy naval vessels to the Sea of Azov, a gulf of the Black Sea between Crimea and the Ukrainian and Russian mainlands.

Stoltenberg repeated a call for Russia to release the sailors and ships and allow unhindered access to Ukrainian ports in the Sea of Azov.

He said he expected ministers to "convey a very clear message to Russia" but refused to offer any fresh practical support measures for Kiev, simply outlining the ways NATO has raised its profile in the Black Sea.

"NATO has already increased our presence in the Black Sea－significantly more days with NATO ships at sea this year than last year, and we have more air policing, ... more presences in the Black Sea in general," Stoltenberg told reporters on Monday.

"We will of course closely monitor the situation in that region also in light of what we saw a few days ago."

A European diplomat said that no boats would be sent in response to the Ukrainian request and that the idea had not even been formally suggested at NATO. Ukraine is a "partner country" for NATO but not a full member.

Last week's incident was the first open military confrontation between Russia and Ukraine since 2014, when Crimea was incorporated into Russia following a local referendum.

Pompeo's goal

Meanwhile, US Secretary of State Mike Pompeo will press allies to meet their military spending targets and talk about Moscow on his NATO trip, according to a statement issued by the US State Department on Monday.

The US government has been criticizing European nations for failing to meet the official annual military spending target of 2 percent of GDP set by NATO.

According to NATO figures, only five of 29 members have met their military spending targets this year - Estonia, Greece, Latvia, the United Kingdom and the United States.

AP/XINHUA