German Chancellor Angela Merkel has said there is "no military solution" to the Ukraine conflict after President Petro Poroshenko asked for NATO naval support in his country's standoff with Russia.
Blaming Russia for the tensions, Ms Merkel said: "We ask the Ukrainian side too to be sensible because we know that we can only solve things through being reasonable and through dialogue because there is no military solution to these disputes".
Russia fired on and then seized three Ukrainian ships on Sunday, accusing them of illegally entering its waters in the Sea of Azov and detaining their crew, in a dramatic spike in tensions that raises fears of a wider escalation.
Kiev accused Russia, which annexed the Crimea peninsula from Ukraine in 2014, of launching "a new phase of aggression".
Poroshenko asked Germany and other NATO countries in comments to Bild newspaper today to "relocate naval ships to the Sea of Azov in order to assist Ukraine and provide security".
Ukraine is not a NATO member but has established close ties with the US-led military alliance, especially since the 2014 Crimea annexation.
Speaking at a German-Ukrainian business forum, Ms Merkel said she would discuss the conflict with Russian President Vladimir Putin at a G20 summit in Argentina this weekend.
She said a bridge from the Russian mainland to Crimea that Putin opened in May had already restricted shipping access to the Sea of Azov and therefore to the Ukrainian port of Mariupol.
"The full blame for this goes to the Russian president," she said.
"Now what I want is that the facts of what happened are put on the table, that the (crew) are released, and that no confessions are coerced like we have seen on television."
"I would also support keeping things calm, but we must also ensure that a city like Mariupol that relies on access to the sea ... is not simply cut off so that large parts of Ukraine can no longer be easily reached."