If further measures are deemed necessary in the future, analysts say the bank could decide to purchase large amounts of financial assets such as government bonds in the open market, a step which can drive rates down further and add newly created money to the economy. But that's a drastic step — and analysts say the bank will only use it if its current efforts don't work as expected.
One risk factor is a sudden shock to business and investor confidence if the conflict between Russia and Ukraine escalates. NATO says Russia has some 20,000 troops massed on Ukraine's border as Ukrainian forces battle pro-Russian separatists.
A further intensification of fighting or outright invasion by Russia could lead the European Union and United States to impose new sanctions on Russia, disrupting trade. Uncertainty over what the impact could be on the global economy and markets could make businesses hold off on investing and consumers on spending — not what the modest recovery needs right now.
Other recent signs have been mixed. Surveys of purchasing managers point up. But Italy's economy, the eurozone's third-largest, slid into recession in the second quarter, shrinking by 0.2 percent after a 0.1 fall in the first quarter. Two straight quarters of contracting output is one common definition of recession.
Low inflation is another worry for the ECB, at only 0.4 percent in the year to July. Too-low inflation has raised fears the eurozone may slip into outright deflation, a crippling downward price spiral in which people postpone purchases because they think goods will become cheaper.
Economist Christian Schulz at Berenberg Bank said the ECB will keep asset purchases — also known as quantitative easing — in reserve so it will have a powerful tool to use if Russian President Vladimir Putin escalates the conflict.
"Putin, not low inflation, is the real risk to the eurozone," he said.
ECB President Mario Draghi has indicated that asset purchases are possible in the future. His words have helped the ECB on one front at least — getting the euro exchange rate lower. On Wednesday, it fell to a nine-month low against the dollar of $1.3333.
The prospect of more money being created through a monetary stimulus is one of the reasons why the euro has been in retreat over the past couple of months. That's good news for the ECB as it helps make exports cheaper — good for growth — and raises the price of imports — good for inflation.