Russian President Vladimir Putin suggested that he could order his troops to try to seize more land in Ukraine to protect bordering Russian territory. The threat made Tuesday carries questionable credibility because the Kremlin lacks full control over areas it already annexed. In some of his most detailed remarks about the war in months, the Russian leader also asserted that Ukrainian forces had suffered “catastrophic” losses in a new counteroffensive. He said he was not contemplating a new troop mobilization, as many Russians have feared. But he did not rule out another troop call-up later.