NATO Secretary General Mark Rutte is warning that a Chinese invasion of Taiwan could push Russia to attack Europe at the same time, a bad sign for European security and a push for allies to arm up faster.

• Rutte says NATO must prepare for a "two-theater" war, with fighting in Europe and the Indo-Pacific at once.
• The logic: if China moves on Taiwan or anywhere along the first island chain, it would likely pressure Russia to hit Europe to split Western forces.
• He urged Europe to strengthen its own defenses as the threat from the east keeps growing.
• Allies are nervous that Trump's six-month review of US troops in Europe, launched in July, could end with fewer American forces on the continent.
• Rutte says he is "not worried" about a US drawdown, and wants America to stay strong in the Indo-Pacific as well.

Outlook: Expect more pressure on European governments to raise defense spending and plan for a war on two fronts while the US troop review plays out.